Fungi are eukaryotic organisms with cell walls made of chitin. Most are made of thin, branching threads called hyphae, which together form a network called a mycelium. Fungi are heterotrophic: they secrete enzymes onto their food and absorb the soluble products (extracellular digestion). Most fungi are saprotrophs that feed on dead matter, but some are parasites that feed on living organisms and cause disease.Fungi produce huge numbers of tiny, lightweight spores, which are easily carried by wind, water, animals or contact. Spores germinate when they land in warm, moist conditions, and hyphae then grow into the host tissue.Fungal diseases are especially important in plants, where they cause a large share of crop losses. Examples include stem rust of wheat (Puccinia graminis), rice blast and ash dieback. Plant pathogenic fungi often enter through stomata or wounds, grow between the host cells and push feeding structures called haustoria into the cells to absorb nutrients.
In humans, most fungal infections affect the skin, nails or mucous membranes, for example athlete's foot and ringworm, and thrush, caused by the yeast Candida albicans. These are usually mild, but fungal infections of the lungs or blood can be life-threatening in people with weakened immune systems.Because fungi are eukaryotes, their cells are similar to ours. This makes it harder to find antifungal drugs that harm the fungus without harming the host.
In humans, most fungal infections affect the skin, nails or mucous membranes, for example athlete's foot and ringworm, and thrush, caused by the yeast Candida albicans. These are usually mild, but fungal infections of the lungs or blood can be life-threatening in people with weakened immune systems.Because fungi are eukaryotes, their cells are similar to ours. This makes it harder to find antifungal drugs that harm the fungus without harming the host.